The invention relates to a polishing pad having a transparent window through which an optical beam is transmitted for an optical apparatus to detect the status of a workpiece during a polishing operation.
The invention resides in a polishing pad for use with a polishing fluid, wherein the polishing pad has, a polishing layer, a window in an opening through the polishing layer, and a fluid impermeable layer spanning across the polishing layer and the window and the opening to provide an uninterrupted continuous barrier to leakage of polishing fluid, the fluid impermeable layer having thereon an adhesive that forms bond seals with the polishing layer and the window. An advantage is that the fluid impermeable layer, being uninterrupted, avoids a tendency to produce leakage paths due to bending during routine handling, or due to exertion of polishing pressure during use of the polishing pad, or due to small voids or gaps in the adhesive. A further advantage is that the bond seals minimize wetting by the polishing fluid of the interface between the adhesive and each of the polishing layer, the window and the fluid impermeable layer.